The present invention relates to an ultrasonic microscope having in addition to an ultrasonic head an optical head, by means of which both ultrasonic observation and optical observation can be selectively performed by changing the heads with the aid of a slide mechanism.
Heretofore, there has been utilized an ultrasonic microscope having both an ultrasonic head including an ultrasonic transducer and an optical head including an objective lens, by means of which ultrasonic and optical images of a specimen can be observed selectively. In the ultrasonic microscope mentioned above, it is often necessary to observe the same region of the specimen both with ultrasonic observation and with optical observation. However in this known ultrasonic microscope, since the objective lens and the ultrasonic head have substantially similar dimensions so that the observation axes of the ultrasonic and optical images can not come close to each other, this results in the disadvantage that the regions observed by the ultrasonic head and by the objective lens are greatly shifted from each other.
In this case, in order to correspond these regions precisely with each other, a very cumbersome operation must be performed such that once observed by one head, the specimen is positioned correctly at a visual field of the other head by moving a specimen stage. However, since the visual field of the ultrasonic wave is very small on the order of 0.1 mm square, high accuracy is required for movement of the specimen stage. Further, since contour configurations of the ultrasonic image and the optical image are usually not identical with each other, registration of the ultrasonic and optical images becomes much more difficult. Therefore, it is extremely difficult to position the region correctly at an observation position by a manual operation while observing the specimen image. Moreover, in order to effect a precise positioning use may be made of a driving device which moves the specimen stage for effecting a sub-scanning operation of the ultrasonic observation. In this case, it is almost impossible to effect precise positioning quickly due to a slow movement of the specimen stage and a low positioning accuracy.